This invention relates, in general, to filters, and more particularly to low voltage filters.
It is well known by one skilled in the art that power supply voltages for integrated circuits are constantly being reduced. The reduction in power supply voltages is mainly due to device constraints and to lower power dissipation. For example, complementary metallic oxide semiconductor (CMOS) is currently migrating from a five volt power supply voltage to a three volt power supply voltage.
Active filter designs do not readily translate to a lower power supply voltage. The linear range of a filter is substantially decreased. Lowering power supply voltages reduces bias head room for the active filter circuitry. Other parameters that affect the filter design are tuning range, power supply noise rejection, circuit complexity, and total power dissipation.
It would be of great benefit if a modular filter could be designed to operate at low voltages whilst being fully differential to maximize noise rejection, and simple in design, and low power.